The present invention relates to a tubular shaped capacitor with axial connections. The tubular structure is preferably formed from a ceramic member which serves as the dielectric and has a layer of metal on each of the outer surface and the inner surface for forming the capacitor plates. A connecting cap is pushed over the end of the ceramic member and is in contact with the outer surface and the cap is thereby connected with the layer of metal forming the capacitor plate on the outer surface. The shell of the connecting cap which is connected to the outer layer exerts, when it is placed on the tubular dielectric member, a pressure whose resultant is less than the allowable compressive strength of the dielectric or ceramic member. A connecting wire is secured at the inner surface and thus connected to the inner layer. The connecting wire is widened within the tubular structure to engage the inner layer and is also beaded at the end of the tubular structure to ensure its securement therein.
A tubular capacitor of this type is shown in West German Provisional Patent (Auslegeschrift) No. 1,130,878 (FIG. 7). Here the connecting cap is arranged in the vicinity of one end and the widened end of a connecting wire is arranged in the region of the other end of the tubular dielectric structure so that with extremely thin wall thicknesses of the dielectric structure, the pushing-on of the connecting cap during manufacture presents a danger of breakage. This possibility of breakage results from the firing shrinkage which occurs upon the sinter firing of the tubular dielectric structure and from the corresponding measurement-tolerance range of the dielectric structure.
A similar tubular capacitor is also shown in West German Pat. No. 828,414 (FIG. 2). In that capacitor, however, the connections are secured in the vicinity of the opposite ends of the tubular dielectric structure and extend parallel to each other. In such a structure, the problem of the possibility of breakage in the utilization of thin walled tubular dielectric structure of the order of 0.1 mm wall thickness also occurs in the same manner as in the first mentioned prior structure.
A tubular capacitor having two stamped metal connections fastened only to the outer surface of the tubular dielectric structure is shown in U.S. Pat. No. 3,129,490 (FIG. 7). The inner plate is extended around one end up to the outer surface. Such a configuration of the plate metal coatings can be produced only at considerable expense.
One method of producing tubular capacitors in which the tubular dielectric structures are pushed over connecting elements which have been stamped out of metal strips and bent, and then soldered together, is shown in West German Unexamined Application for Patent (Offenlegungsschrift) No. 2,263,279. Tubular capacitors are produced by a simple method. However, they do not have axial connections, but instead have radial connections.
As a result of the trend to automatic manufacturing processes, it is desirable to develop components with axial connections and to supply them in belted form. In fact, it is possible, with only slight modifications to employ machines used for the manufacture of capped electrical resistors having axial connecting wires for the manufacture of electrical capacitors as well.
The West German Unexamined Applications for Patent (Offenlegungsschrift) No. 2,650,177 and 2,652,895 show methods for the production of electrical capacitors in which resistor production machines can be used in modified form for constructing the capacitors. In these methods, the supporting bodies are known as layer resistors.
Different forms of the widening of the end of the wire extending into the borehole for electrical components are shown in West German Pat. No. 601,284, West German Pat. No. 965,703, West German Provisional Patent (Auslegeschrift) No. 1,018,123, West German Pat. No. 1,054,541, West German Pat. No. 1,194,945 and West German Unexamined Application for Patent (Offenlegungsschrift) No. 1,790,090. In all of these structures, widening of a connecting wire is shown but these widenings are for capless resistors which are inserted into a blind hole of a supporting body.